Marceda-Veiga 2012 Towards the Conservation Of
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Author's personal copy Rev Fish Biol Fisheries DOI 10.1007/s11160-012-9275-5 REVIEWS Towards the conservation of freshwater fish: Iberian Rivers as an example of threats and management practices Alberto Maceda-Veiga Received: 28 February 2012 / Accepted: 25 June 2012 Ó Springer Science+Business Media B.V. 2012 Abstract The current freshwater fish fauna crisis is ecosystem researchers and stakeholders. Conservation such that natural resource managers urgently need to efforts should be focused on the preservation of identify priorities and understand the management ecological processes, in order to achieve the goals of consequences of actions aimed at maximizing the the Water Framework Directive and guarantee the preservation of biodiversity. Freshwater research is conservation of Iberian native fish species. often poorly linked to conservation ecology; and interdisciplinary studies illustrating examples of Keywords Aquatic conservation Á Management freshwater ecosystem conservation are scarce. The actions Á Endangered fish Á Freshwater Á Iberian Peninsula has a long history of anthropogenic Anthropogenic modifications disturbance that has led to the poor conservation status of its ichthyofauna, with 52 % of species now catalogued as critically endangered, endangered or vulnerable, according to UICN criteria. This paper gives an overview of the main threats (habitat Introduction degradation, hydrological alterations and exotic spe- cies) that have altered the function and connectivity of Freshwater ecosystems are some of the most threa- Iberian rivers. Case-study examples are provided to tened in the world. The loss of their biodiversity analyse the repercussions of these threats and the appears to be more intense than that of any other management actions planned or already performed in habitat (Dudgeon et al. 2006; Clavero et al. 2010; these systems. The interaction of many threats is Olden et al. 2010; Moyle et al. 2011). The number of responsible for native fish decline. However, fresh- endangered freshwater species on the International water managers and researchers should not let the Union for the Conservation of Nature (IUCN) Red List trees prevent them from seeing the overall wood, when has more than tripled since 2003 (Vie´ et al. 2009). This seeking to achieve practical solutions with the best concern is great in regions with a high degree of balanced cost benefit and the collaboration of all endemicity like the Mediterranean area in which 70 % of freshwater species are catalogued as threatened by extinction or are already extinct (Smith and Darwall A. Maceda-Veiga (&) 2005). This percentage is the highest recorded any- Department of Animal Biology (Vertebrates) and where in the world for any taxonomic group (Vie´ et al. Research Institute of Biodiversity (IRBio), Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain 2009). Examples of freshwater fish decline and studies e-mail: [email protected] of population trends are common in the scientific 123 Author's personal copy Rev Fish Biol Fisheries literature (Elvira 1995a, b; Aparicio et al. 2000; information provided may encourage researchers to Leprieur et al. 2008; Maceda-Veiga et al. 2010b; develop practical studies and help resource managers Moyle et al. 2011). Many of these studies have in the conservation of freshwater biota, especially in identified common causes of population decline areas with similar climatic conditions. (Elvira and Almodo´var 2001; Clavero et al. 2004; Nilsson et al. 2005; Dudgeon et al. 2006; Clavero et al. 2010; Gozlan et al. 2010; Olden et al. 2010; Hermoso Methods and Clavero 2011). The poor conservation status of Iberian freshwater fish species requires the design and Sources of information implementation of conservation plans (Filipe et al. 2004; Abell et al. 2007; Araguas et al. 2009; Nel et al. All native freshwater fish species from Iberia were 2009; Hermoso and Clavero 2011; Moyle et al. 2011; considered in the study, including anadromous and Olden et al. 2011). However, examples in the scientific catadromous species (e.g. Anguilla, Salmon, Alosa) literature of management action have long been biased and endemic species present in coastal lagoons (e.g. towards terrestrial ecosystems; research into freshwa- Aphanius, Valencia), but excluding amphidromous ter ecology is still not often linked to conservation species like mugilids. The IUCN Red List of ecology. Thus, interdisciplinary practical studies Threatened Species (www.iucnredlist.org) was used illustrating examples of freshwater fish conservation to compile information on the conservation status, are scarce (Lake et al. 2007; Nel et al. 2009; Strayer threats, population trends and conservation tools and Dudgeon 2010). required. This information, often used in similar Natural resource managers need to identify prior- studies (e.g. Clavero et al. 2010), was collected ities and understand the management consequences of through a regional assessment of fish endemic to the actions aimed at maximizing the preservation of Mediterranean basin by some 20 experts in fish biol- biodiversity (Dudgeon et al. 2006; Helfman 2007; ogy and conservation (Smith and Darwall 2005). Strayer and Dudgeon 2010; Olden et al. 2011; The examples used to illustrate potential or actual Grantham et al. 2012). Species decline may result management actions are based on reports and papers from the synergy of several impacts or from the identified via an intensive literature review, and by specific effect of one, whose proportional contribu- personal communication with freshwater managers tions to fish decline may also vary over time (Groom and researchers or with ecosystem stakeholders. The et al. 2006; Olden et al. 2010; Hermoso and Clavero main threats discussed are based on IUCN assessment 2011; Grantham et al. 2012). While large-scale and on the experience of researchers working on assessment can highlight the overall extent of the freshwater ecosystems, especially in regions with freshwater crisis, severity and causes are best under- similar climatic conditions (Doadrio 2001; Elvira and stood, even in large climatic areas (Hermoso and Almodo´var 2001; Sabater 2008; Sabater et al. 2009; Clavero 2011), by studies that focus on the regional Clavero et al. 2010, Elosegui et al. 2011; Hermoso and level (Moyle et al. 2011). The Iberian Peninsula Clavero 2011; Grantham et al. 2012). provides a suitable scenario for analysing the decline of freshwater fish because it has a high degree of fish endemicity and a long history of anthropogenic Conservation status of Iberian ichthyofauna disturbance (e.g. dams, forest exploitation, water extraction, extensive agriculture, water pollution, The conservation status of many species is critically industrialization, extensive forest fires, exotic intro- endangered, endangered or vulnerable. Populations ductions, fisheries) (Sabater et al. 2009; Clavero et al. are declining sharply, like freshwater ichthyofauna 2010; Hermoso et al. 2011; Maceda-Veiga and De elsewhere (Moyle et al. 2011; Hermoso and Clavero Sostoa 2011). This paper gives an overview of the 2011) (Fig. 1, Appendix 1). Freshwater fish diversity main threats to Iberian freshwater ichthyofauna. It in the Iberian Peninsula is characterised by a high shows the consequences that various management degree of endemicity (73 % of species are endemics to actions have had or may have on their conservation, the Iberian Peninsula) and restricted distribution using interdisciplinary case-study examples. The ranges (Fig. 2, Appendix 1). Exotic fish species 123 Author's personal copy Rev Fish Biol Fisheries the relative proportion of exotic species might be attenuated by the description of new native species (Kottelat and Freyhof 2007; Appendix 1). Threats to freshwater biodiversity According to UICN, the main threats to Iberian ichthyofauna are water extraction (including hydro- logical infrastructures) and introduced species, followed by climate constraints, pollution and over- exploitation (Table 1). These threats are shared with other Mediterranean regions (Hermoso and Clavero 2011). With a view to developing appropriate man- agement actions, the following subsections summarize how these and other reported threats to freshwater fish fauna in Iberia are affecting all key components of these freshwater ecosystems (i.e. riparian coverage, Fig. 1 Current conservation status of Iberian native fish species water flow level and quality, gravel bed streams and based on UICN criteria: CE critically endangered, E endangered, aquatic biota), together with the action of natural NT near threatened, V vulnerable, LC least concern and ND restrictions from the Mediterranean climate (i.e. forest without enough data fires and droughts). account for 42 % of Iberian freshwater fish, which is Hydrological infrastructures and water extraction similar to that reported for other European countries (Elvira 1995a, Doadrio 2001, Leprieur et al. 2008, Water extraction, considered one of the main threats Maceda-Veiga et al. 2010a, Appendix 2). However, to freshwater ecosystems worldwide, is a particular Fig. 2 Population trends of the native freshwater fish fauna in Iberian Peninsula 123 Author's personal copy Rev Fish Biol Fisheries Table 1 Threats to Iberian native freshwater fish fauna and However, a multi-year study on the effects of drought proposed management actions based on IUCN criteria on Guadiana fish populations showed that in dry years % large barbels (Luciobarbus sclateri) and chub (Squa- lius torgalensis) declined, but small fish species like